Push-rod-operating mechanism



Dec. 25, 1928.

w. A. SEAMAN PUSH ROD OPERATINGMECHANISM 2 Sheet-Sheet 1 Filed Sept. 23,1926 M/fdfl? A 1560/7705 gwve'ntox Gwynne-11 Dec. 25, 1928.

W. A. SEAMAN PUSH ROD OPERATING MECHANISM- 2 SheetS-Sheet 2 Filed Sept.23, 1926 i A, deaman gnm'ntoz Wad/6% ing the rapid reciprocation of thetappet.

Patented Dec. 25; 1928.

WILLIAM: A. SEAMAN, OF SAGINAW, MICHIGAN.

PUSH-ROD-OPERATING MECHANISM.

Application filed September 28, 1926. Serial No. 137,366.

is manually adjustable, and is so adjusted as to leave a slight space orclearance between the tappetand the adjacent end of the valve f stem orpush rod operated thereby; This space may be reduced-through accurateadj ustment of the parts so as to be substantially infinitesimal inmeasurement, but some space must be left to accommodate the expansion ofparts due to the variation of temperature in operation of the engine.The space necessarily existing between the tappet and the valve stem orpush rod gives rise to objectionable ta-pping or hammering noises, dueto sudden forcible contact of metallic parts dur- Further, the tappet,under the rapid li ting impulses of the operating cam, is driven againstthe valve stem or push rod with such force and so often as to causeobjectionable wearing of parts and undesirable vibration and stressthroughout the valve mechanism, as well as causing, through wear, theclearance space to increase materially, thereby increasing the noise andcausing other inefficiences to arise.

The present invention has for its primary object the provision of atappet whichv in operation, will constantly or continuously contact withthe end of the valve stem or push rod for thereby closing the clearancespace which ordinarily must be left.

A further object is to provide a t-appet of e the above character whichis extensible and compressible for automatically lengthening andshortening to accommodate the variation in the length of the variousparts of the valve mechanism caused by expansion and contraction fromtemperature changes.

Another object is to provide a tappet embodying a pair of telescopicallyand slidably associated members having an incompressible liquid cushiontherebetween, means to supply the liquid of the cushion under pressurebetween said tappet members whereby the tappet is lengthened for keepingthe clearance the liquid pressure of the cushion during the retreatlngmovement of the cam whereby the tappet is allowed to shorten forpermit-" ting complete return movement of the push rod and completeclosing of the valve associated therewith.

, A still further object is to relieve the liquid pressure of thecushion by esca e of the liquid from between thetappet mem ers to apoint between the contacting surfaces of the tappet and the cam, wherebywhen oil is employed as the 11 uid of the cushion, a film of oil will behad etween the surfaces for reducing wear. vibration and noise.

Still another object is to sup ly the li uid or oil of the cushion sothat e ective lu rication is had between the tappet and its guide orslide bearing for further reducing wear and promoting the ease ofmovement of the tappet. A further object is to provide a self-adjustmgand shock absorbing ltappet which employs a liquid cushion and which isentirely devoid of frail and objectionable metallic springs and movablecheck valves.

Another object is to provide a tappet of the Figure 2 is a horizontalsection taken upon line 2-2 of Figure 1;

Figure 3 is a section taken on the line 3-3 of Figure 1;

Figure 4 is a horizontal section taken on the line 4-4 of Figure 1;

Figure5 is a vertical section taken substantially upon line 5 -5 ofFigure 1; and

Fi ure 6 is a fragmentary vertical sectiona view illustrating amodification of a rtlon of the embodiment of the invention illustratedin Figures 1 to 5 inclusive.

Referring more in .detail to the drawings, 5 indicates-a conventionalform of guide or slide bearing which is usually formed integral with thecylinder block of an internal combustion engine and which is providedwith a vertical cylindrical opening in which the tappet of the presentinvention is slidably fitted for vertical reciprocation. As is usual inconstructions of this kind a rotatable cam shaft 6 is horizontallydisposed below and slightly spaced from the guide or slide bearing 5 andhas a cam 7 fixed thereon in position to engage the adjacent lower endof the tappet mounted in the slide bearing 5 as shown clearly in Figures1 and 5. The adjacent lower end of the push rod or valve stem adapted tobe engaged by the upper end of the tappet for being lifted to effectopening of the associated valve of the engine when the tappet is raisedby the cam 7 is indicated at 8.

The present tappet includes a tappet body 9 which is centrally bored sothat the upper end of the body is open and the bore is of cylindricalform, and so that the lower end of the tappet body is provided with abottom wall having an integral shoe or plate 10 adapted to ride on theedge or surface of the cam 7, the tappet body 9 being provided with acylindrical outer bearing surface adapted to snugly engage the bearingsurface of the guide or slide bearing 5. The tappet further includes atubular or cylindrical member or plunger 11 which is slidably fittedwithin the tappet body 9 and adapted to project slightly above the upperend of the latter, the plunger or tubular member 11 including acylindrical body which is centrally bored so as to be open at its upperend and closed at its lower end.

A valve lifting member is engaged in the tubular member or plunger 11,and as shown in Figures 1 to 5 inclusive, this valve lifting member mayconsist of a bolt 12 having its stem adjustably threaded in the upperend of the plunger 11 so that its head is disposed to engage the lowerend of the push rod or valve stem 8. As is well known in'the art, theadjustment of the bolt 12 is maintained by means of a 'amb nut 13threaded upon the stem of the bolt 13 and engaged a ainst the upper endof the tappet, the nut 13 being engaged against the upper end of thetappet member or plunger 11 in the present instance.

The guide or slide bearing 5 is provided near its lower end with atransverse opening that communicates with the bearing op-.

ening of the guide 5 and has a nipple 14 threaded therein, which nippleis coupled as indicated at 15 with the adjacent end of an oil pressureline 15 that may extend from clearly shown in Figure 5, the plunger 11is provided with a reduced lower end portion so as to leave an annularspace as at 18 between such reduced end portion of the plunger 11 andthe inner surface of the'tappet body 9. Extending transversely throughthe wall of the tappet body 9 at suitable uniformly spaced points are aplurality of openings 19 which communicate at their outer ends with theannular groove 17 and at their inner ends with the annular space 18between the reduced end of the plunger 11 and the tappet body 9. Theopenings 19 provide constant communication between the groove 17 and thespace 18 because the reduced end portion of plunger 11 is of suificientlength to extend above the openings 19 even when the tappet iscompletely compressed-or collapsed with the plunger 11 eompletedlywithin the tappet body 9. Disposed within and seated upon the bottom orlower end wall of the tappet body 9 is a resilient block or rubbercushion 20 adapted to be engaged by the lower end of the plunger 11 whenthe tappet shortens for absorbing shock.

Extending through the cushion 20 and the lower end of the tappet body 9is an oil passage or opening 21 arranged to lead oil from the lower endof the tappet body 9 onto the bearing surface or edge of cam 7. p

In operation, the engine is started in the usual way so as to causerotation ofcam shaft 7 and the cam 7 carried thereby, at which time oilis supplied under pressure through the line 16 into groove 17 andthrough openings 19 into the annular space 18, the oil ultimatelyfinding its way from the space 18 to a point between the cushion 20 andthe lower end of plunger 11. Prior to starting the engine the screw 12may be adjusted so as to leave a slight clearance space between the headof the same and the lower end of the rod or stem 8 in the usual way whenthe plunger 12 is substantially engaged at its lower end with the IIIcushion 20. However, as soon as the oil under pressure finds its waybetween the cushion 20 and the lower end of plunger 11, the latter willbe raised so as to close said clearance space and engage the head ofscrew or bolt 12 with the lower end of rod or stem 8. As the cam 7 turnswith the shoe or plate 10 riding on the base circle of said cam. thetappet will be constantly engaged with the cam and the rod or stem 8,and oil will find its way through openin or passage 21 onto the surfaceof the cam or minimizing wear. Upon continued rotation of cam 7 theprojection of the latter will ride into engagement with the shoe orplate 10 and thereby effect lifting of the tappet and consequently causelifting of rod or stem 8 for openin the associated valve, not shown.When this lifting action of the cam is had the opening 21 is lesssecurely closed b the-cams'urface, and the liquld pressure 0 the liquidcushion between the plunger and the tappet body is partially relieved bya more pronounced flow of the oil through the passage 21 onto the cam 7.I This provides a film of oil on the cam surface so as to morethoroughly lubricate at a time when lubrication is more needed, and suchfilm of oil will also serve to present a cushion-like medium between thecontacting surfaces of the tappet body and the cam. At this time, thecam 7 will be starting upon its retreating period of movement forallowing the tappet and the push rod or stem to lower. This loweringaction is effected and accelerated by the closing spring of the valvewhich tends to force the plunger 11 dow'nwardly into the valve body 9 asallowed by the reliefof pressure through the opening 21. Consequently,the tappet will automatically shorten dnnng its lowering movement forinsuring permission of complete closing of the valve of the engine. Assoon as the tappet completely lowers it will have been shortened to itsextreme extent, at which time the lower end of the plunger 11 willcontact the cushion 2-0 so that any likely shock is absorbed. The partsare then disposed for a new cycle of operation as described above.

oil between the cushion 20 and the lower end of plunger 11. Naturally,considerable of the oil fed to the groove 17 will find its way betweenthe cont-acting surfaces of the guide 5 and the tappet body 9 so thatlubrication is had at this point for preventing wear of these parts.

The plunger 11 may be substituted for the plunger 11 of Figure 5 invalve operating mechanism wherein the elements 12 and 13 are notemployed. In such instances, the plunger is not interiorly threaded andthe push rod or valve stem 8 constitutes the valve lifting member and isextended into the plunger so as to directly contact with the lower endof the latter.

From the foregoing description .it is believed that the construction andoperation as well as the advantages of the present inven tion will bereadily understood and appreciated by those skilled in the art.

Minor changes may be made without departing from the spirit and scope ofthe invention as claimed.

What I claim as new is 1. A self-adjusting tappet forpush rod operatingmechanisms, including a pair oftelescopically and slidably associatedmembers, means to supply oil under pressure between said tappet membersfor providing a liquid cushion therebetween and lengthening the tappetfor maintaining constant contact o f the tappet with the cam and thepush rod, said tappet having a longitudinal opening through the lowerend thereof to allow the oil to flow from between the tappet members toa point between the tappet and the cam and to partially relieve theliquid. pressure of the cushion during the retreating movement of thecam whereby the tappet is allowed to shorten for permittin completereturn movement of the push rodi 2. A tappet device for push rodoperatin mechanisms, wherein the tappet is interposed between anoperating cam and the push rod,

.to automatically partially relieve the liquid pressure ofthecushionduring the retreating movement of the cam, whereby the tappet is allowedto automatically shorten for permitting complete return movement of thepush rod, and an elastic cushion interposed between the tappet membersfor absorbing shock incident to sudden shortening of the tappet.

3. A self adjusting tappet for a push rod operating mechanism,comprising a pair of telescopically and slidably associated tappetmembers, means to supply oil under pressure between said tappet membersfor providing a liquid cushion therebetween for lengthening the tappetto maintain constant contact of the tappet with the cam and push rod,said tap-pet having a longitudinal opening through the lower end thereofto allow the oil to flow from between the tappet members to a pointbetween the tappet and the cam and to partially relieve the liquidpressure of the cushion during the retreating movement of the camwhereby the tap-pet isallowed to shorten to permit complete returnmovement of the push rod, one of said tappet members comprising acentrally bored body having a cylindrical exterior bearing surface inthe lower end of which said longitudinal opening is formed, and theother tappet member comprising a plunger slidably fitted-in the tappetbody and having a closed lower end.

4. In combination, a guide, a tappet vertically slidable in said guideand comprising a pairv of telescopically and slidably associatedmembers, a lifting cam engaged. with the lower end of the outer one ofthe tappet members, arranged to be engaged by the upper end of the innerone of said tappet members, and means for continuously supplying oilunder pressure between said tappet members to provide a liquid cushiontherebetween and to lengthen the tap-pet for maintaining engagement ofthe tappet members with the cam and the valve lifting member and forsimultaneously supplying the oil between the cooperating surfaces of theguide and the tappet and the cooperating surfaces of the cam and thetappet, said oil supplyin means between the connecting surfaces of thetappet and the cam constituting means for relieving the pressure of theliquid cushion between the tappet members upon retreating movement ofthe cam and the lowering of the tappet and valve lifting member.

5. In combination, a guide, a tappet vertically slidable in said guideand comprising a pair of telescopic-ally and slidably associatedmembers, a lifting cam engaged with the lower end of the outer one ofthe tappet members, a valve lifting member arranged to be engaged by theupper end of the inner one of said tappet members, and means forcontinually supplying oil under pressure between said tappet members toprovide a liquid cushion therebetween to lengthen the tappet formaintaining engagement of the members with the cam and valve liftingmember and for simultaneously supplyin the oil between the cooperatingsurfaces of t e guide and the tappet and the cooperating surfaces of thecam and the tappet, said oil supplying means comprising an oil pressureline communicating with the bearing opening of the tappet guide, saidouter tappet member being provided with an external annular groove andsaid inner member being reduced at the lower end, the tappet memberhaving the external annular groove having transverse apertures placingthe groove in communication with the space provided between the tappetmembers by the reduced end of the other member whereby constantcommunication is had between the oil pressure line and the space betweenthe tappet members.

6. A tappet device for push rod operating mechanism, wherein the tappetis interposed between an operating cam and the push rod, comprising apair of telescopically associated members, a bearing guide designed toreceive said members, one of said members being designed to rest upon anoperating cam and the other being designed for connection with the pushrod, and means for forcing a liquid under pressure between the inner endof the inner one of said members and the outer member to lengthen thetappet to maintain constant contact between the same and the cam andpush rod, and means for relieving the pressure through that surface ofthe tappet member against which said cam bears,

at certain periods during the rotation of the cam.

In testimony whereof I aifix my signature.

WILLIAM A. SEAMAN.

